256 lines
7.2 KiB
C
256 lines
7.2 KiB
C
/**
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* eCryptfs: Linux filesystem encryption layer
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*
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* Copyright (C) 2004-2006 International Business Machines Corp.
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* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
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* Tyler Hicks <tyhicks@ou.edu>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#include <net/sock.h>
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#include <linux/hash.h>
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#include <linux/random.h>
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#include "ecryptfs_kernel.h"
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static struct sock *ecryptfs_nl_sock;
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/**
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* ecryptfs_send_netlink
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* @data: The data to include as the payload
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* @data_len: The byte count of the data
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* @msg_ctx: The netlink context that will be used to handle the
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* response message
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* @msg_type: The type of netlink message to send
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* @msg_flags: The flags to include in the netlink header
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* @daemon_pid: The process id of the daemon to send the message to
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*
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* Sends the data to the specified daemon pid and uses the netlink
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* context element to store the data needed for validation upon
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* receiving the response. The data and the netlink context can be
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* null if just sending a netlink header is sufficient. Returns zero
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* upon sending the message; non-zero upon error.
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*/
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int ecryptfs_send_netlink(char *data, int data_len,
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struct ecryptfs_msg_ctx *msg_ctx, u16 msg_type,
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u16 msg_flags, pid_t daemon_pid)
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{
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struct sk_buff *skb;
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struct nlmsghdr *nlh;
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struct ecryptfs_message *msg;
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size_t payload_len;
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int rc;
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payload_len = ((data && data_len) ? (sizeof(*msg) + data_len) : 0);
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skb = alloc_skb(NLMSG_SPACE(payload_len), GFP_KERNEL);
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if (!skb) {
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rc = -ENOMEM;
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ecryptfs_printk(KERN_ERR, "Failed to allocate socket buffer\n");
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goto out;
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}
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nlh = NLMSG_PUT(skb, daemon_pid, msg_ctx ? msg_ctx->counter : 0,
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msg_type, payload_len);
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nlh->nlmsg_flags = msg_flags;
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if (msg_ctx && payload_len) {
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msg = (struct ecryptfs_message *)NLMSG_DATA(nlh);
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msg->index = msg_ctx->index;
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msg->data_len = data_len;
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memcpy(msg->data, data, data_len);
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}
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rc = netlink_unicast(ecryptfs_nl_sock, skb, daemon_pid, 0);
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if (rc < 0) {
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ecryptfs_printk(KERN_ERR, "Failed to send eCryptfs netlink "
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"message; rc = [%d]\n", rc);
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goto out;
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}
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rc = 0;
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goto out;
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nlmsg_failure:
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rc = -EMSGSIZE;
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kfree_skb(skb);
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out:
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return rc;
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}
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/**
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* ecryptfs_process_nl_reponse
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* @skb: The socket buffer containing the netlink message of state
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* RESPONSE
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*
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* Processes a response message after sending a operation request to
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* userspace. Attempts to assign the msg to a netlink context element
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* at the index specified in the msg. The sk_buff and nlmsghdr must
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* be validated before this function. Returns zero upon delivery to
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* desired context element; non-zero upon delivery failure or error.
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*/
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static int ecryptfs_process_nl_response(struct sk_buff *skb)
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{
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struct nlmsghdr *nlh = nlmsg_hdr(skb);
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struct ecryptfs_message *msg = NLMSG_DATA(nlh);
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int rc;
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if (skb->len - NLMSG_HDRLEN - sizeof(*msg) != msg->data_len) {
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rc = -EINVAL;
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ecryptfs_printk(KERN_ERR, "Received netlink message with "
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"incorrectly specified data length\n");
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goto out;
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}
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rc = ecryptfs_process_response(msg, NETLINK_CREDS(skb)->uid,
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NETLINK_CREDS(skb)->pid, nlh->nlmsg_seq);
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if (rc)
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printk(KERN_ERR
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"Error processing response message; rc = [%d]\n", rc);
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out:
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return rc;
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}
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/**
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* ecryptfs_process_nl_helo
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* @skb: The socket buffer containing the nlmsghdr in HELO state
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*
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* Gets uid and pid of the skb and adds the values to the daemon id
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* hash. Returns zero after adding a new daemon id to the hash list;
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* non-zero otherwise.
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*/
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static int ecryptfs_process_nl_helo(struct sk_buff *skb)
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{
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int rc;
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rc = ecryptfs_process_helo(ECRYPTFS_TRANSPORT_NETLINK,
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NETLINK_CREDS(skb)->uid,
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NETLINK_CREDS(skb)->pid);
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if (rc)
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printk(KERN_WARNING "Error processing HELO; rc = [%d]\n", rc);
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return rc;
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}
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/**
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* ecryptfs_process_nl_quit
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* @skb: The socket buffer containing the nlmsghdr in QUIT state
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*
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* Gets uid and pid of the skb and deletes the corresponding daemon
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* id, if it is the registered that is requesting the
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* deletion. Returns zero after deleting the desired daemon id;
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* non-zero otherwise.
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*/
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static int ecryptfs_process_nl_quit(struct sk_buff *skb)
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{
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int rc;
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rc = ecryptfs_process_quit(NETLINK_CREDS(skb)->uid,
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NETLINK_CREDS(skb)->pid);
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if (rc)
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printk(KERN_WARNING
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"Error processing QUIT message; rc = [%d]\n", rc);
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return rc;
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}
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/**
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* ecryptfs_receive_nl_message
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*
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* Callback function called by netlink system when a message arrives.
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* If the message looks to be valid, then an attempt is made to assign
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* it to its desired netlink context element and wake up the process
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* that is waiting for a response.
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*/
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static void ecryptfs_receive_nl_message(struct sock *sk, int len)
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{
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struct sk_buff *skb;
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struct nlmsghdr *nlh;
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int rc = 0; /* skb_recv_datagram requires this */
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receive:
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skb = skb_recv_datagram(sk, 0, 0, &rc);
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if (rc == -EINTR)
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goto receive;
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else if (rc < 0) {
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ecryptfs_printk(KERN_ERR, "Error occurred while "
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"receiving eCryptfs netlink message; "
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"rc = [%d]\n", rc);
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return;
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}
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nlh = nlmsg_hdr(skb);
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if (!NLMSG_OK(nlh, skb->len)) {
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ecryptfs_printk(KERN_ERR, "Received corrupt netlink "
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"message\n");
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goto free;
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}
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switch (nlh->nlmsg_type) {
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case ECRYPTFS_NLMSG_RESPONSE:
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if (ecryptfs_process_nl_response(skb)) {
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ecryptfs_printk(KERN_WARNING, "Failed to "
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"deliver netlink response to "
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"requesting operation\n");
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}
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break;
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case ECRYPTFS_NLMSG_HELO:
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if (ecryptfs_process_nl_helo(skb)) {
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ecryptfs_printk(KERN_WARNING, "Failed to "
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"fulfill HELO request\n");
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}
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break;
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case ECRYPTFS_NLMSG_QUIT:
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if (ecryptfs_process_nl_quit(skb)) {
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ecryptfs_printk(KERN_WARNING, "Failed to "
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"fulfill QUIT request\n");
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}
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break;
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default:
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ecryptfs_printk(KERN_WARNING, "Dropping netlink "
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"message of unrecognized type [%d]\n",
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nlh->nlmsg_type);
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break;
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}
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free:
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kfree_skb(skb);
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}
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/**
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* ecryptfs_init_netlink
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*
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* Initializes the daemon id hash list, netlink context array, and
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* necessary locks. Returns zero upon success; non-zero upon error.
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*/
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int ecryptfs_init_netlink(void)
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{
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int rc;
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ecryptfs_nl_sock = netlink_kernel_create(NETLINK_ECRYPTFS, 0,
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ecryptfs_receive_nl_message,
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NULL, THIS_MODULE);
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if (!ecryptfs_nl_sock) {
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rc = -EIO;
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ecryptfs_printk(KERN_ERR, "Failed to create netlink socket\n");
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goto out;
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}
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ecryptfs_nl_sock->sk_sndtimeo = ECRYPTFS_DEFAULT_SEND_TIMEOUT;
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rc = 0;
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out:
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return rc;
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}
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/**
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* ecryptfs_release_netlink
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*
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* Frees all memory used by the netlink context array and releases the
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* netlink socket.
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*/
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void ecryptfs_release_netlink(void)
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{
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if (ecryptfs_nl_sock && ecryptfs_nl_sock->sk_socket)
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sock_release(ecryptfs_nl_sock->sk_socket);
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ecryptfs_nl_sock = NULL;
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}
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